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Herein, the effect of molybdenum (Mo) and postrolling cooling processes on the mechanical properties and microstructure transformation characteristics of an X80 thick‐wall high‐strength pipeline steel are deeply investigated. The results reveal that the yield strength and tensile strength of the steel are enhanced with Mo addition at the equalization temperature of 480 °C at a cooling rate of 25 °C s−1, accompanied by the improvement in the yield ratio. However, when the postrolling cooling temperature is reduced to 380 °C, the mechanical properties of steels with Mo‐free and 0.29 wt% Mo are comparable. The mechanistic study indicates that the Mo addition would inhibit the transformation from deformed austenite to polygonal ferrite, and promote the transformation of acicular ferrite/granular bainite at medium–low temperatures, as well as significant differences in the volume fraction, size, and morphology of martensite/austenite (M/A) in the matrix. Notably, the volume fraction of M/A decreases from 7.2% to less than 1.0% with Mo content increasing, while its average size also reduces from 1.5 to less than 1.0 μm. And the fine, spheroidal, and dispersed M/A is found to play a vital role in the high‐strength and excellent low‐temperature toughness of the steel. [ABSTRACT FROM AUTHOR]

The need to implement projects for the decarbonization of technological processes is relevant in connection with the international climate agenda. To reduce greenhouse gas emissions, especially in Scope 3, carbon sequestration activities are indispensable, which can be implemented in various ways. Of great interest is the creation and implementation of industrial carbon sequestration technologies that use the existing oil and gas infrastructure, and in addition, allow obtaining additional benefits by increasing oil and gas recovery. The implementation of this technology largely depends on the environmental and economic feasibility of the project, which is influenced by the selected technologies for capturing and cleaning gas from impurities, the length of the pipeline to the field, a reasonable injection technology, an emergency monitoring system, and many other factors. For this reason, scientific and practical research in this direction are of practical importance and are quite relevant. The purpose of our study is aimed at reducing the risks of oil and gas companies in the transportation of carbon dioxide from the place of formation to the place of use when injected into the reservoir to enhance oil or gas recovery. The article presents the results of the analysis of possible emergency situations during the transportation of carbon dioxide to the place of injection. Recommendations are given to prevent them, namely, equipping the route of the pipelines being designed with pressure sensors, justifying the reaction time to stop the compressor equipment, which is no more than 6 minutes and the departure of technical specialists to the emergency facility no earlier than 15 minutes after the incident. It is noted that in order to reduce pipeline corrosion and prevent carbon dioxide leaks, it is recommended to comply with the conditions under which the gas is in a supercritical state, in addition, to purify the gas from impurities in the transported carbon dioxide stream and use a corrosion-resistant material for the manufacture of the pipeline. [ABSTRACT FROM AUTHOR]

This investigation focuses on the ranking of pipeline leakage susceptibility of two categories of pipeline systems. One consists of three oilfield water-handling pipeline systems and the other consists of five dry crude systems. Online corrosion monitoring (OCM) method was used for both systems, forthermore, in-line inspection (ILI) method, with Magnetic Flux leakage (MFL) tool, was also used for the dry crude systems. The OCM leakage susceptibility potential is derived from the combined severity of general corrosion, pitting corrosion, fluid corrosivity and sessile bacteria population density in the process streams. The ILI leakage susceptibility potential is derived from the average number of corrosion anomalies greater than 10% of the wall thickness and the maximum depth of the anomalies (as percentage of the wall thickness). In spite of such distinctions, the ranking of pipeline leakage susceptibility for the five dry crude pipeline segments turned out to be identical for the two methodologies. [ABSTRACT FROM AUTHOR]

A better use of space is achieved when different networks and systems, such as AC transmission lines, transportation systems, and pipelines share the same right-of-way. However, the electromagnetic coupling between the systems may cause the appearance of dangerous conditions for people due to exposure to high touch voltages, as well as for pipelines, caused by the activation of the AC corrosion phenomenon. These dangerous conditions require that during design the possible risks are assessed, and the corresponding mitigation actions are determined. This paper presents a simplified methodology for risk assessment using a practical approach and analytical expressions that can be easily implemented from information known while designing. Likewise, results are included for a case study that allow validating the proposed methodology and demonstrating the importance of this type of analysis. [ABSTRACT FROM AUTHOR]

This study investigates the monitoring of corrosion in the distribution network pipeline in Patna (Bihar), India, using a weight loss method and an image processing technique. The seven coupons were injected into the pipeline of the distribution network and ejected after 45, 90, 135, 180, 225, 270, and 315 days. The corrosion rate was calculated by weighing the initial and final weight of coupons. It was found to be 0.035, 0.078, 0.048. 0.035, 0.028, 0.052, and 0.039 mm/year during 45, 90, 135, 180, 225, 270, and 315 days, respectively. Scaling rate found at 45, 90, 135, 180, 225, 270, and 315 days was 0.006, 0.037, 0.042, 0.049, 0.011, 0.018, and 0.033 mm/year, respectively. Surface analysis was performed using the scanner method and MATLAB software. Coupons were first scanned using a scanner adjusted to 4800 ppi. A scanned image was imported into MATLAB. An algorithm was used based on color analysis. The output of a text file was generated that gave the corrosion pit in terms of pixels. The MATLAB analysis shows that the surface corrosion area sum of both sides of the coupon was 6.24, 6.39, 6.49, and 6.48 cm2 in 45, 90, 135, and 180 days, respectively. This study concludes that scale formation on the pipe surface decreased the corrosion rate. Corrosion and scaling were found in the opposite trend. SEM analysis shows that pitting corrosion was increasing with increasing duration of time. Physicochemical analysis shows that the water was alkaline. The presence of a greater concentration of hardness, alkalinity, and less concentration of chloride, sulfate, and DO water was found to have a scaling tendency. XRD analysis of iron dust represents the presence of salts in water, which is responsible for the scaling behavior of water. [ABSTRACT FROM AUTHOR]

Copyright of Oilfield Chemistry is the property of Sichuan University, Oilfield Chemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rapidly increasing production volume of clean hydrogen creates challenges for transport infrastructure. This study improves understanding of hydrogen transport options in Europe and provides more detailed analysis on the prospects for hydrogen transport in Finland. Previous studies and ongoing pipeline projects were reviewed to identify potential and barriers to hydrogen transport. A fatigue life assessment tool was built because material challenges have been one of the main concerns of hydrogen transportation. Many European countries aim at utilizing existing gas infrastructure for hydrogen. Conducted studies and pilot facilities have provided promising results. Hydrogen reduces the fatigue life of the pipeline, but existing pipelines can be used for hydrogen if pressure variation is maintained at a reasonable level and the maximum operation pressure is limited. Moreover, the use of existing pipelines can reduce hydrogen transport costs, but the suitability of every pipeline for hydrogen must be analyzed, and several issues such as leakage, leakage detection, effects of hydrogen on pipeline assets and end users, corrosion, maintenance, and metering of gas flow must be considered. The development of hydrogen transport will vary within countries depending on the structure of the existing gas infrastructure, and on the future hydrogen use profile. [Display omitted] • H 2 pipeline transportation projects in Europe were reviewed. • Use of linear elastic fracture mechanics fatigue assessment tool was demonstrated. • 80 bar natural gas pipeline could be converted to 45–55 bar H 2 pipeline. • Existing natural gas network will be utilized for H 2 transportation in the future. • Further research needed to ensure feasibility of H 2 transportation in existing grid. [ABSTRACT FROM AUTHOR]

In recent years, the increase in energy prices and demand has been driven by the post-pandemic economic recovery. Of the various energy sources, oil and natural gas remain the most important source of energy production and consumption after coal. Oil and gas pipelines are a key component of the overall energy infrastructure, transporting oil and gas from mines to end users, so the reliability and safety of these pipelines is critical. The oil and gas industry incurs large expenses for the removal of failures related to, among others, corrosion of pipelines caused by the presence of Hg, CO2 H2S, carbonates and chlorides in reservoir waters. Therefore, pipeline operators must constantly monitor and prevent corrosion. Corrosion failure losses are a major motivation for the oil and gas industry to develop accurate monitoring models using non-destructive NDT methods based on test results and failure frequency observations. Observing the locations of frequent pipeline failures and monitoring and applying corrosion protection to pipelines play an important role in reducing failure rates and ultimately increasing the economic and safety performance of pipelines. Monitoring and prevention efforts support the decision-making process in the oil and gas industry by predicting failures and determining the timing of maintenance or replacement of corroded pipelines. We have presented methods of prevention through the use of corrosion inhibitors in crude oil and natural gas transmission pipelines, as well as various factors that influence their application. In this article, a review of corrosion rate monitoring systems is conducted, and a range of control and monitoring scenarios is proposed. This knowledge will aid scientists and practitioners in prioritizing their policies, not only to choose the appropriate monitoring technique but also to enhance corrosion protection effectiveness. [ABSTRACT FROM AUTHOR]

Corrosion is still the most common contributor to failures in Water Distribution Networks (WDNs), causing detrimental techno-socio-economic impacts. Although the corrosion process has been the subject of several studies, factors influencing this process remain a source of contention due to the complexity of the process and its influence by the surrounding environment. Considering the prior reviews, this comprehensive review is considered an early attempt to thoroughly cover the most influential corrosion factors in water pipelines. Corrosion factors have been classified into three main categories: 1) environmental factors; soil factors, external factors, and stray current factors; 2) pipe-related factors, and 3) operational factors. A fault tree analysis diagram was used to map, discuss, and analyze all significant corrosion causes of the buried water pipelines to facilitate easy visualization from basic factors to their intermediate and parent factors. Furthermore, the techno-socio-economic impacts of corrosion on water pipelines and beyond are appropriately addressed to demonstrate the issue's multi-dimensional importance. The research is expanded to rank these factors using the fuzzy analytical hierarchy process to provide a better understanding of the currently focused research investigation and to enable the extraction of gaps and existing limitations in scholarly literature. The findings revealed that water quality is the most investigated factor, followed by electrical infrastructure and soil quality. Conversely, operational factors exhibit the greatest relative weight (0.428), followed by environmental factors (0.337). These findings highlight areas where further research is needed, and the article proposes potential directions for future studies to address these gaps. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Polymer‐clay nanocomposites have attracted significant research interest for more than a decade for various applications. The structural, thermal, and electrical stability of a nanocomposite determines its durability and long‐term application under sunlight and UV photodegradation of dyes, lithium nanopolymer batteries, and petroleum pipeline corrosion protection, in addition to the effect of high temperatures, e.g., in the Sahara. In the present work, the intercalation of montmorillonite clay within the polymer structure was done by organophilization using hexadecyltrimethylammonium bromide. The obtained nanocomposite was characterized in terms of its structural, electrical, and thermal properties using Fourier transform infrared spectroscopy, the four‐pin method, and differential scanning calorimetry, respectively. The effect of photodegradation on polymer nanocomposite properties was assessed under sunlight and UV radiation under laboratory conditions. The obtained results highlighted the good barrier properties of the nanocomposite, attributed to the clay part. [ABSTRACT FROM AUTHOR]

Internal corrosion is a major concern in ensuring the safety of transmission and gathering pipelines in Structural Health Monitoring (SHM). It usually requires numerous sensors deployed inside the piping system to comprehensively cover the locations with high corrosion rates. This study presents a hybrid modeling strategy using Computational Fluid Dynamics (CFD) and Genetic Algorithm (GA) to improve the sensor placement scheme for corrosion detection and monitoring. The essence of the proposed strategy harnesses the well-validated physical modeling capability of the CFD to simulate the oil-water two-phase flow and the stochastic searching ability of the GA to explore better solutions on a global level. The CFD-based corrosion rate prediction was validated through experimental results and further used to form the initial population for GA optimization. Importantly, fitness was defined by considering both sensing effectiveness and cost of sensor coverage. The hybrid modeling strategy was implemented through case studies, where three typical pipe fittings were used to demonstrate the applicability of the sensor layout design for corrosion detection in pipelines. The GA optimization results show high accuracy for sensor placement inside the pipelines. The best fitness of the U-shaped, upward-inclined, and downward-inclined pipes were 0.9415, 0.9064, and 0.9183, respectively. Upon this, the hybrid modeling strategy can provide a promising tool for the pipeline industry to design the practical placement. [ABSTRACT FROM AUTHOR]

Two groups of steels industrially smelted differing in carbon and manganese content, as well as microalloying elements, are studied. It is established that an increase in carbon content does not adversely affect oilfield pipe steel corrosion resistance. Provision of the required strength level may be achieved by increasing the carbon and manganese contents, which is also expedient from an economic point of view. At the same time, absence of unfavorable structural components in steel and steel low contamination with nonmetallic inclusions of an unfavorable composition ensures a high level of steel corrosion resistance. [ABSTRACT FROM AUTHOR]

Corrosion under insulation is a major economic concern in the safe operations of water, oil and gas steel pipes. Herein, the external corrosion of X80 pipeline steel was examined beneath a disbonded insulation in groundwater containing sulphate-reducing bacteria (SRB). The results show that the steel under the insulation exhibited different electrochemical behaviour from the uninsulated sample in the bulk solution. A galvanic effect was detected between the steel under insulation and the uninsulated sample. Spectroscopic analysis reveals the rust layer of the insulated steel immersed in the SRB-inoculated groundwater was enriched by FeS from microbial metabolism. The steel under insulation recorded severe localised perforation, while corrosion severity was reduced on the uninsulated sample. Diffusion of ions, film development and insulation degradation played important roles in steel corrosion. [ABSTRACT FROM AUTHOR]

This study aims to study the safety of oil and gas pipelines under stress corrosion conditions and grasp the corrosion damage situation timely and accurately. Consequently, a non-destructive testing method combining magnetic flux leakage testing technology and a kernel function extreme learning machine improved by genetic algorithm (GA-KELM) is proposed. Firstly, the variation of the corrosion defect dimension and profile with time is obtained by numerical simulation. At the same time, the distribution of the magnetic flux leakage signal under different defect conditions is analyzed and studied. Finally, feature selection is carried out on the magnetic flux leakage signal distribution curve, and GA-KELM is used to predict the depth and length of corrosion defects so as to realize the non-destructive testing of the pipeline defects. The results show that different geometric features result in different magnetic flux leakage signal distributions. There is a corresponding relationship between the defect dimension and extreme value, area, and peak width of the magnetic flux leakage signal distribution curve. The GA-KELM prediction model can effectively predict the depth and length of corrosion defects, and the prediction accuracy is better than the traditional extreme learning machine prediction model. [ABSTRACT FROM AUTHOR]

The fluctuations of the Pipe-to-Soil Potential (PSP) in buried pipes are influenced by the geoelectric field induced by changes in the Earth's magnetic field, which can accelerate pipeline corrosion. Monitoring data of PSP along China's West–East Gas Pipeline near the lake indicates obvious tidal changes. This study proposes that the periodic movement of the conductivity boundary of the seepage area near the lake shore caused by tides is the fundamental cause of the tidal changes in PSP. The movement of the boundary changes the range of the H polarization of the geoelectric field, resulting in periodic changes in the PSP of the pipeline outside the seepage area. To investigate this mechanism, a dynamic boundary model of conductivity in the seepage area of Sailimu Lake in Xinjiang was established, and the characteristics of PSP at different distances from the boundary were analyzed using electromagnetic field finite element method and DSTL pipeline model. The study compared the simulation results of the model with the PSP data of the cathodic protection station and PSP monitoring station near Sailimu Lake, during a geomagnetic disturbance on September 23–24, 2016. The results of the study, as well as the corrosion of the test strips along the lake, verified the validity of the boundary change mechanism and model of the seepage zone. This study provides a theoretical basis for corrosion protection of pipelines near the lake's edge. [ABSTRACT FROM AUTHOR]

Copyright of Corrosion & Protection in Petrochemical Industry is the property of Corrosion & Protection in Petrochemical Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Corrosion & Protection in Petrochemical Industry is the property of Corrosion & Protection in Petrochemical Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Corrosion & Protection in Petrochemical Industry is the property of Corrosion & Protection in Petrochemical Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The ultrasonic guided lamb wave approach is an effective non-destructive testing (NDT) method used for detecting localized mechanical damage, corrosion, and welding defects in metallic pipelines. The signal processing of guided waves is often challenging due to the complexity of the operational conditions and environment in the pipelines. Machine learning approaches in recent years, including convolutional neural networks (CNN) and long short-term memory (LSTM), have exhibited their advantages to overcome these challenges for the signal processing and data classification of complex systems, thus showing great potential for damage detection in critical oil/gas pipeline structures. In this study, a CNN-LSTM hybrid model was utilized for decoding ultrasonic guided waves for damage detection in metallic pipelines, and twenty-nine features were extracted as input to classify different types of defects in metallic pipes. The prediction capacity of the CNN-LSTM model was assessed by comparing it to those of CNN and LSTM. The results demonstrated that the CNN-LSTM hybrid model exhibited much higher accuracy, reaching 94.8%, as compared to CNN and LSTM. Interestingly, the results also revealed that predetermined features, including the time, frequency, and time–frequency domains, could significantly improve the robustness of deep learning approaches, even though deep learning approaches are often believed to include automated feature extraction, without hand-crafted steps as in shallow learning. Furthermore, the CNN-LSTM model displayed higher performance when the noise level was relatively low (e.g., SNR = 9 or higher), as compared to the other two models, but its prediction dropped gradually with the increase of the noise. [ABSTRACT FROM AUTHOR]

This research utilizes Ultrasonic Guided Waves (UGW) to inspect corrosion-type defects in steel pipe walls, providing a solution for hard-to-reach areas typically inaccessible by traditional non-destructive testing (NDT) methods. Fundamental helical UGW modes are used, allowing the detection of defects anywhere on the pipe's circumference using a limited number of transducers and measurements on the upper side of the pipe. Finite element (FE) modeling and experiments investigated generating and receiving UGW helical waves and their propagation through varying corrosion-type defects. Defect detection is based on phase delay differences in the helical wave's signal amplitude peaks between defective and defect-free regions. Phase delay variations were noted for the different depths and spatial dimensions of the defects. These results highlight the phase delay method's potential for NDT pipeline inspection. [ABSTRACT FROM AUTHOR]

The influences of Mg2+ and Ca2+ on the short-term (1800 s) corrosion behavior of X100 pipeline steel were investigated in a sodium chloride (NaCl) solution saturated with CO2. Either Ca2+ or Mg2+ in the solution inhibited the short-term corrosion of X100 pipeline steel, with the corrosion current density decreasing from 262.4 μA cm−2 to 163.5 μA cm−2 or 80.8 μA cm−2. During longer-term (8−48 h) immersion, the Mg2+ inhibited the formation of the protective scale, whereas the Ca2+ accelerated the formation of the scale. Further, an experimental equation establishing the relationship between the precipitation rate of the corrosion scale and the exposure time was proposed to quantitatively study the effects of Mg2+ and Ca2+ on the precipitation rate of the corrosion scale. [ABSTRACT FROM AUTHOR]

Objective The corrosion problem of amine solution regeneration system is solved to ensure the safe, stable and long-term operation of the sulfur recovery unit. Methods (1) Based on the operating conditions and material selection of amine solution regeneration system in a refinery, combined with the corrosion problems that have occurred, the main corrosion/damage types, corrosion sites and corresponding severity were determined. (2) Blocks were divided according to the medium type, and the threshold values of key parameters and the off-limits response strategies were proposed. (3) The corrosion control strategy was applied in the industrial field, and its effect on improving the corrosion problem was verified. Results Under the condition of using the recommended materials, the overall corrosion rate of the amine solution regeneration system could be confined to less than 0.05 mm/a by setting the temperature and flow rate thresholds, controlling the specific indexes of amine, and adopting the corresponding response strategy when the parameters exceeded the standard. Conclusions By implementing corrosion control strategy in the key corrosion regions, the corrosion degree of equipment and pipelines in the amine solution regeneration system has been significantly alleviated, which is helpful for prolonging single operation cycle and achieving cost reduction with efficiency increased. [ABSTRACT FROM AUTHOR]

Pipe with an outer diameter of 159 mm and a design wall thickness of 5 mm in a gas mine was corroded and perforated, resulting in gas collection interruption and significant economic loss. The maximum corrosion pit length is 40.7 mm. To explore the specific causes of pipeline failure, the pipelines were analyzed by means of scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and x-ray diffraction (XRD). The results show that the tube section meets the mechanical property standard. The proportion of carbon(C), oxygen (O2) and sulfur in pipeline corrosion products is more than 35 wt.%, resulting in the formation of 1200-1300a.u in other areas of the inner wall of the pipeline. Ferrous carbonate (FeCO3) and ferrous sulfide (FeS) are attached to the tube wall near the 6 o'clock direction. To prevent pipeline failure, CO2, H2S and other impurities should be removed in time. [ABSTRACT FROM AUTHOR]

Carbon steel flowlines transporting hydrocarbon fluids are susceptible to internal corrosion in the aqueous phase at the base (6 o'clock position) and in aqueous condensed droplets at the top (12 o'clock position). Respectively, these issues are known as "bottom‐of‐the‐line" corrosion and "top‐of‐the‐line" corrosion and inhibitors that are used to control internal pipeline corrosion need to be effective at both locations. Here, we explore whether 2‐mercaptobenzimidazole (2‐MBI), 2‐phenyl‐2‐imidazoline (2‐PI), 2‐amino‐5‐ethyl‐1,3,4‐thiodiazole (2‐AETD), are able to control CO2 corrosion simultaneously at both the top‐ and the bottom‐of‐the‐line in the presence and absence of acetic acid, a common minor constituent of produced hydrocarbon fluids. The performance of the species varied between highly effective (2‐MBI), moderately effective (2‐AETD) to ineffective (2‐PI). Inhibition was effective at both bottom‐ and top‐of‐the‐line, and with acetic acid present. Given that the vapor pressure of these species is negligible, it is suggested that they are carried from the bulk phase to the top‐of‐the‐line dissolved in aerosol droplets rather than in the vapor phase. [ABSTRACT FROM AUTHOR]

Cathodic protection allied to a polymeric coating is one of the most employed techniques to protect buried steel pipelines against corrosion. Nevertheless, cathodic disbondment, a phenomenon associated with such protection in high‐performance coatings such as (three‐layer polyethylene [3LPE]), still concerns the oil and gas segment regarding pipeline integrity. The present work was part of a Program of Integrity Management and studied in field‐like conditions the influence of cathodic potential, type of soil and coating system on the coating disbondment of buried pipelines for 450 days. The coating systems herein studied simulated the patching between aged (coal tar) and new coatings (3LPE), a standard procedure during damaged pipeline repair. Results pointed out that the combination between aged (coal tar) and new coatings (3LPE) in a pipe segment reduced coating disbondment when compared to the systems where 3LPE was the sole type of coating. Moreover, it was shown that more cathodic potentials (<−1100 mV) and the aggressiveness of the industrial soil herein tested induced disbondment diameters as high as 15.5 mm. [ABSTRACT FROM AUTHOR]

Burst pressure is an essential parameter to measure the residual bearing capacity of pipelines with corrosion defects. Accurate prediction of burst pressure is beneficial to evaluate the remaining life of pipelines. The traditional estimation formulas mainly focus on single-point corrosion but seldom consider the case of multipoint corrosion. Although DNV-RP-F101 considers multipoint corrosion, this method only considers the influence of axial spacing of adjacent corrosion defects on burst pressure but does not consider the influence of circumferential spacing. This work refers to the pipe corrosion criterion (PCORRC) and DNV-RP-F101 methods and modifies the calculation formula of the PCORRC method by introducing (D−t). The average relative error is only 11.46%, which is 27.65% lower than the previous formula. In addition, this paper presents a method for estimating the burst pressure of pipelines with multipoint corrosion defects. This method considers not only the axial spacing between defects but also the circumferential spacing. The results show that the maximum relative error is 6.52%. A machine learning modeling framework for predicting burst pressure in multipoint corroded pipelines is proposed. The case using radial basis function neural network as the prediction tool shows that the average Pearson correlation coefficient of the prediction results in the test set is 0.903, indicating that the prediction performance is good. [ABSTRACT FROM AUTHOR]

Water vapor penetrating an annulus causes condensation and corrosion and endangers the safe operation of the flexible riser. However, in current studies, the condensation of water vapor in the annulus is modeled based on the film condensation hypothesis, which assumes that the metal material is uniformly corroded. This assumption differs from the true corrosion incidents, which are usually initiated by localized corrosion. To further study the condensation law of water vapor in a flexible riser annulus, the evolution of water vapor condensation on the wall surface of a sapphire reactor was evaluated using an annular condensation experimental device. A water vapor condensation growth model was established to analyze the condensation law and its influencing factors. The results show that the maximum radius of condensate droplets on the annular wall surface is approximately 0.48 cm, the average radius of droplets is approximately 0.35 cm, and the volume of condensate that can be accommodated in the 18 × 18 mm simulation area is approximately 0.5 cm3. After the droplet reaches the departure radius and falls off a surface, the time of recondensation is faster than that of the first condensation. The condensation surface coverage increases rapidly in the early stage and then gradually slows down. After stabilization, the maximum coverage can reach 80%. Parameter analysis suggests that the number of fixed nucleation points on the condensation wall affects the time to reach the departure radius and the increasing rate of surface coverage. However, the number of fixed nucleation points has minimal influence on the departure radius and coverage outcomes. The findings of this study establish a theoretical foundation for predicting dropwise condensation behaviors in annulus of pipelines and developing corrosion protection strategies that modify the wall contact angle or structure. [ABSTRACT FROM AUTHOR]

The paper focuses on the experimental investigation and mathematical modeling of the corrosion of steel when a film of water flows over its surface. The experimental monitoring of corrosion dynamics in the flowing film was carried out using a laboratory pilot model, exploited in such a way as to obtain data necessary to identify some characteristic parameters of the mathematical model of this problem. The mathematical model of the case takes into account the transfer of oxygen through the liquid film flowing on the surface of the corroding plate where the chemical surface processes characteristic of corrosion occur (dissolution of Fe, oxidation of Fe2+ to Fe3+, formation of surface deposit, etc.). Experimental measurements were used to identify the parameters of the mathematical model, especially the reaction constant of the Fe dissolution rate and the surface oxidation yield of Fe2+ to Fe3+. Calculation of the correlation coefficients for the apparent constant surface reaction rate and process factors showed that they correlate strongly and non-linearly with the Reynolds number (Re) of the film flow, with the cumulative flow duration, and with the cumulative standby time of the experiments. Using the dynamics of the resistance to the transfer of oxygen through the rust film and the dynamics of its thickness resulting from the specific flow of rust deposition, the apparent oxygen diffusion coefficient through the rust film formed on the plate was expressed. [ABSTRACT FROM AUTHOR]

Buried piping is subject to soil corrosion, which can be prevented by combining coatings and cathodic protection to maximize corrosion control. However, even with both methods, coatings are subject to damage from external factors and various causes. Buried piping may expose the metal and alter the current flow, which in turn causes corrosion. Therefore, this study analyzed the effect of detection electrode spacing on the direct current voltage gradient (DCVG) magnitude formed for coated pipelines buried in the soil. The DCVG was measured using a real-time coating defect detection system. FEM model simulations were carried out, and then the result was compared to the measured DCVG magnitude. When the spacing of the detection electrodes increased, the detected signal and signal location changed. The detection reliability increased as the noise signal is eliminated at the optimum detection electrode spacing. However, the detection reliability decreased at higher selection electrode spacing as the noise signal and detected signals together were eliminated. The location of the detected signal shifted as the spacing of the detection electrodes increased due to the change in the detection reference point and signal magnitude. [ABSTRACT FROM AUTHOR]

Hydrogen can degrade the mechanical properties of steel components, which is commonly referred to as "hydrogen embrittlement" (HE). Quantifying the effect of HE on the structural integrity of components and structures remains challenging. The authors investigated an X70 pipeline steel through uncharged and hydrogen-charged (notched) tensile tests. This paper presents a combination of experimental results and numerical simulations using a micro-mechanics-inspired damage model. Four specimen geometries and three hydrogen concentrations (including uncharged) were targeted, which allowed for the construction of a fracture locus that depended on the stress triaxiality and hydrogen concentration. The multi-physical finite element model includes hydrogen diffusion and damage on the basis of the complete Gurson model. Hydrogen-Assisted degradation was implemented through an acceleration of the void nucleation process, as supported by experimental observations. The damage parameters were determined through inverse analysis, and the numerical results were in good agreement with the experimental data. The presented model couples micro-mechanical with macro-mechanical results and makes it possible to evaluate the damage evolution during hydrogen-charged mechanical tests. In particular, the well-known ductility loss due to hydrogen was captured well in the form of embrittlement indices for the different geometries and hydrogen concentrations. The limitations of the damage model regarding the stress state are discussed in this paper. [ABSTRACT FROM AUTHOR]

Understanding the microcracking mechanisms and associated acoustic characteristics involved in the creep of heterogeneous granite at the grain scale is of high importance in practical engineering. To perform this task, a series of creep numerical simulations were conducted on granite with a single pre-existing open flaw using a grain-based parallel-bonded stress corrosion model. We investigated the effect of flaw inclination angle on the creep behavior and discussed the significance of microstructure. The results suggest that the axial strain, secondary creep strain rate and time-to-failure all depend strongly and nonlinearly on the flaw inclination angle. Creep failure is mainly induced by the initiation, propagation and coalescence of microcracks, and the dominant types are inter-grain tension cracks and intra-grain tension cracks. The b value, source types and distribution of acoustic emission events are associated with the flaw inclination angle and driving-stress ratio. Tensile sources account for the majority of the total number of acoustic emission sources, while shear and implosive acoustic emission sources are larger in magnitude. The model with higher heterogeneity creeps at a faster rate under the same applied constant axial stress. The higher number of acoustic emission events at each creep stage of such model indicates that the relatively heterogeneous microstructure provides more paths for the growth of microcracks during creep loading. As the heterogeneity increases, the secondary creep strain rate rises and the b value decreases. The position of the final macroscale shear band of pre-cracked granite is more affected by pre-existing flaw compared to its microstructure. Highlights: An extended grain-based parallel-bonded stress corrosion (GB-PSC) model was proposed to simulate the creep and associated acoustic behavior of granite. Voronoi tessellations to provide a more realistic representation of the microstructure of granite. Effects of open flaw inclination angle on creep behavior of pre-cracked granite were systematically investigated and the significance of microstructure were discussed. The acoustic emission characteristics of mineral boundaries and interiors during creep loading were obtained using the moment tensor analysis. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to investigate the effects of the cementite morphology on the hydrogen trapping behavior in low-alloy pipeline steel. Design/methodology/approach: In this study, the hydrogen trapping behavior in low-alloy pipeline steel was quantitatively studied by a combination of microstructural observations, electrochemical hydrogen permeation experiments and thermal desorption spectroscopy (TDS) analyses. Findings: P-1 and P-2 steels are two samples with different microstructures. The morphology of cementite precipitates in the P-1 and P-2 steels was different. Lamellar cementite is present in P-2 steel and only granular cementite in P-1 steel, which led to a better irreversible hydrogen trapping ability of P-2 steel, which was confirmed by subsequent hydrogen permeation and TDS experiments. Originality/value: The study of these deep hydrogen trap sites is helpful in improving the hydrogen embrittlement resistance of low-alloy pipeline steels. [ABSTRACT FROM AUTHOR]

The in situ spraying method is widely used because of its advantages as a trenchless pipeline repair technology, including a fast construction speed and close bonding between the repair lining layer and the reinforced concrete pipe. However, current research on high-performance spray repair materials, the bearing capacity of pipelines before and after repair, and the failure modes between the two interfaces after repair is insufficient. Through laboratory tests designed with multiple sets of control tests, this paper outlines the bearing capacity of reinforced concrete pipelines with corrosion thinning defects repaired with ultra-high-performance concrete. The variation law of the residual bearing capacity of reinforced concrete pipes and the influence of different corrosion degrees, repair thicknesses, and interface forms on the bearing capacity of reinforced concrete pipes were studied following UHP-ECC for pipe repair. The results showed that the bearing capacity of the structure decreased with an increase in the corrosion thickness of the pipeline. After repair with ultra-high-performance concrete, the bearing capacity of corroded pipelines greatly improved. When the corrosion and repair thicknesses were the same, the bearing capacity of the repaired pipeline with different interface forms was very different. After the interface was implanted with nails, spray repair was carried out and the bearing capacity of the pipeline improved the most, followed by the naturally bonded interface. When plastic film was pasted on the repair interface, the bearing capacity of the pipeline improved the least. [ABSTRACT FROM AUTHOR]

Gas–liquid intermittent flow is a kind of flow pattern that distinguishes itself from the conventional flow by the apparent non-steady feature, which causes serious corrosion issues, including localized corrosion. Although it widely exists in wet gas pipelines, how the gas–liquid intermittent flow influences CO2 corrosion of pipeline steels remains a problem to be clarified. In this work, a testing device that enables good simulation of gas–liquid intermittent flow in wet gas pipelines under various conditions was developed and used to perform experimental studies, combining electrochemical tests and corrosion morphology observations. The result shows that flow velocity and gas–liquid ratio act together to affect the CO2 corrosion behavior of X70 steel in typical intermittent flow conditions. The flow velocity has a more profound effect on the corrosion rate, while the gas–liquid ratio is associated with the occurrence of localized corrosion. The effect of the gas–liquid ratio on corrosion behavior was discussed. [ABSTRACT FROM AUTHOR]

Offshore pipelines are subjected to stresses (e.g., from fluid flow, mechanical vibration, and earth movement). These stresses, combined with corrosive environments and in the presence of trace gases (O2, CO2), can increase the pipeline's corrosion rate and potentially lead to cracking. As such, the impact of trace gases such as CO2 (linked to enhanced oil recovery and carbon capture and sequestration) on corrosion is key to determining whether pipelines are at increased risk. American Petroleum Institute (API) 5L X70 and X100 were exposed as stressed C-rings (80% or 95% of yield strength). The tests were conducted with either N2 (control) or CO2 bubbled through 3.5% NaCl, at either 5 °C or 25 °C. Linear polarization resistance was used to assess corrosion rate, while morphology and variation were determined using optical microscopy (generating metal loss distributions) and scanning electron microscopy. The control experiment (N2) showed that corrosion rates correlated with temperature and stress. In this low O2 environment, both alloys showed similar trends. Under CO2 exposure, all samples showed accelerated corrosion rates; furthermore, the morphologies generated were different for the two alloys: undercutting corrosion with discontinuous microcracks (X70) or deep, wide ellipses (X100). Understanding these changes in corrosion response is key when selecting materials for specific operational environments. [ABSTRACT FROM AUTHOR]

The perforation of shale gas transportation pipelines occurred frequently in the form of pitting corrosion because of microbiologically influenced corrosion (MIC). In this study, the pitting corrosion behavior of L245N pipeline steel in shale gas produced water with sulfate reducing bacteria (SRB) and iron oxidizing bacteria (IOB) was studied. The results indicate that the development of pitting corrosion can be divided into three stages. The compact biofilm was formed in the second stage and facilitated the appearance of pits. The major mechanism of pit growth was electron uptake from elemental iron by sessile SRB settled in the biofilm. The corrosion prevention strategy was briefly discussed. [ABSTRACT FROM AUTHOR]

With the rapid development and maturity of modern industrial technology, intelligent robot has become an increasingly essential part of our people's work and life. As an important symbol of technological innovation ability and manufacturing level, robot has become an important field of scientific research, and more experts have invested in the research of robot. At present, the more mature robot is industrial robot, which has been successfully applied in actual industrial production, while the more humanized intelligent robot is still in the research stage of the laboratory. According to different application directions, intelligent robots can be divided into pipeline robots, underwater operation robots, flight robots, ground robots, and so on. The pipeline robot can be used to detect the damage and corrosion of the pipeline in the process of use and can clean, weld, and paint the pipeline in harsh environment. Underwater robots can be used in marine water quality research, offshore oil exploration, marine mineral exploration, submarine salvage, etc. Flying robots are mainly used in satellite communication, road condition monitoring, geological exploration, aerial photography, weather forecast, news broadcast, traffic navigation, etc. It is with a variety of intelligent robots for human services, which makes human science and technology more advanced, work and life more convenient. Therefore, it is very important to study the intelligent robot more deeply. In this paper, inventive problem solving theory is integrated into the product ergonomics design, and a product ergonomic design process model based on pattern recognition and TRIZ is constructed. We considered different intelligent robot forms and analyzed them form different perspectives. To validate the overall performance, the systematic experiment is conducted. [ABSTRACT FROM AUTHOR]

The transmission medium of natural gas gathering and transportation pipelines usually contains corrosive gases, which will cause serious corrosion on the inner wall of the pipelines when they coexist with water. Therefore, it is necessary to add corrosion inhibitor to form a protective film to protect the pipeline. The distribution of corrosion inhibitors in a gathering and transportation pipeline in Moxi gas field was studied by combining experiment and simulation. The Pearson function was used to calculate the experimental and simulation results, and the correlation was more than 80%, indicating a high degree of agreement. The simulation results show that: 1 The larger the pipe angle, filling speed and gas flow rate, the smaller the particle size, the better the distribution of corrosion inhibitor particles in the pipe. The filling amount will affect the concentration, but the distribution trend is unchanged; 2 A method to determine the filling mode based on the loss was proposed, and for this pipeline, the loss of corrosion inhibitor was determined to be 5.31 x 10-3 kg/s, and the filling amount was recommended to be adjusted to 20 L/h, which has certain guiding significance for the actual filling strategy of pipeline corrosion inhibitor. [ABSTRACT FROM AUTHOR]

The stress corrosion susceptibility of Q235 buried old pipeline steel welded joint was studied by slow strain rate tensile test. The results showed that the mechanical properties of Q235 steel samples in J6A soil simulation solution were lower than those in the air. The quasi-cleavage fracture morphology was observed on the fracture surface of the samples, and clear stress corrosion cracks were also observed on the side of SSRT samples, indicating that Q235 steel has a certain SCC sensitivity in J6A solution. The corrosion effect of the test medium will be strengthened in the areas with various stress concentrations such as defects and cracks on the surface of Q235 steel, and the effect of external stress will cause non-uniformity of corrosion and strengthen local corrosion. [ABSTRACT FROM AUTHOR]

Multicomponent thermal fluid flooding has become a widely used and very effective heavy-oil recovery technology, but the harsh CO2–O2–Cl− environment can lead to serious corrosion perforation failure of the pipeline. Therefore, the influence of O2 content and main controlling factors on corrosion perforation were investigated through a weight-loss experiment, corrosion defect test, characterization and grey correlation method. The results showed that, with the increase in O2 content, the general corrosion rate and localized corrosion rate increased. The uneven protection performance of the product after the addition of O2 was found to be the key cause of localized corrosion. In addition, the synergistic effect of O2–Cl− promoted the lateral and longitudinal expansion of pits. The results of the grey correlation showed that the temperature (30–120 °C) had a greater impact on localized corrosion compared with the content of O2 (0–0.045 MPa) and Cl− (0–16,000 mg/L). [ABSTRACT FROM AUTHOR]

Corrosion under disbonded coatings (CUDC) remains a major unsolved issue and a prime risk to underground steel structures such as buried gas pipelines. CUDC could not be effectively mitigated by conventional cathodic protection (CP) or be detected through usual inspection and survey technologies due to CP shielding. This article provides a brief review of recent progresses made through laboratory and field probing of CUDC and its influence factors. Discussions on CUDC processes and mechanisms are made based on results from an extensive laboratory and field-testing program using electrode array-based corrosion probes. It is shown that CUDC is affected not only by well-known factors such as the CP level, but also by coating disbondment geometry and soil conditions especially the seasonal dry-wet changes in soil saturation status. These findings have led to improved understanding of CUDC, and could lead to the development of better CUDC mitigation and control methods. [ABSTRACT FROM AUTHOR]

In-line inspection (ILI) is important to pipeline integrity management since it can detect pipeline defects and identify potential failure locations through periodical examinations. However, effectively evaluating defects based on ILI data is challenging. Measurements of ILI are easily influenced by instrument performance and maintenance activities, leading to unmatched and imbalanced data. Poor ILI data make it difficult to establish defect growth models based on multiple inspections. This study conducted comprehensive analysis of ILI data for evaluating corrosion defects of a steel pipeline. First, statistical analysis was performed on raw data to visualize distributions of corrosion depths and number of corrosions. Second, hierarchical clustering method was used to classify corrosion severity levels based on features of corrosion depth and estimated repair factor. The interaction effect between adjacent corrosions was considered. Machine learning methods, including k-nearest neighbor, support vector machine, random forest, and light gradient boosting machine were used to explore the relationship between the location parameters of adjacent corrosions and severity levels. Then, maximum corrosion depths and corrosion density were filtered from raw ILI data of multiple inspections, which were critical for pipeline failure prediction. Finally, distribution parameters were fitted to establish stochastic growth models on maximum corrosion depth and corrosion number density. This study presents data analytics based approach to obtain valid information from ILI data in practice. [ABSTRACT FROM AUTHOR]

This paper reports a study on the influence of soil environmental factors on the corrosion of underground pipeline steel. By designing a three-factor and three-level orthogonal experiment, the correlations between three typical soil environmental factors, temperature, Cl− salt content and SO42− salt content, and the corrosion rate of pipeline steel were analysed. According to the range analysis, the main controlling factor is temperature, and the optimal solution, that is, the highest corrosion rate of pipeline steel, is when the Cl− salt content is 2.0%, the SO42− salt content is 0.3%, and the temperature is 10 °C. Considering the influence of the above three factors on the corrosion rate of steel samples, five regression models were established to analyze the sensitivity and influence degree of the three factors on the corrosion rate. Compared with the multiple primary regression model, the multiple quadratic regression model obtained an average relative error of only 2.62%, indicating certain feasibility of the model. The corrosion rate of steel samples was positively correlated with the temperature and the salt content of Cl−, that is, the higher the ambient temperature, the higher the salt content of Cl−, and the faster the corrosion. It also showed a first upward-then downward trend with the salt content of SO42−, that is, when the salt content of SO42− increased to a certain value, the occurrence of corrosion would be inhibited. The residual analysis indicated that the influence of the salt content of SO42− on the corrosion rate was not significant. Establishment of a corrosion prediction model has certain theoretical significance and application value to improve the reliability of underground pipelines, prolong the service life of pipelines, reduce production costs, and ensure life safety and economic benefits. [ABSTRACT FROM AUTHOR]

Although hydrogen embrittlement (HE) has been the subject of extensive research over the past century, a systematic study on the HE susceptibility of steels under different electrochemical charging conditions has been lacking. This study specifically targets this knowledge gap by evaluating the HE behaviour of a typical pipeline steel X65 after hydrogen-charging in acidic, neutral, and alkaline electrolytes that simulate various industrial environments. Results from a series of experiments show that the HE susceptibility of X65 steel varied significantly with hydrogen-charging electrolytes and, to a smaller extent, with electrochemical charging variables. The highest and lowest HE susceptibilities were found from specimens charged in acidic and alkaline electrolytes, respectively. An increase in yield strength was observed for almost all hydrogen-charged specimens, regardless of the charging conditions. Under severe electrochemical charging conditions, blistering was detected and mechanical properties were substantially decreased. Discussion has been made in comprehending these relationships. • HE behaviours of steel in different electrolytes simulating industrial environments. • HE susceptibility of steel varied significantly with hydrogen-charging electrolytes. • The highest HE susceptibility was observed on specimens charged in acidic electrolyte. • An increase in yield strength was observed for hydrogen-charged steel specimens. • Blistering was observed when specimens were hydrogen charged under severe conditions. [ABSTRACT FROM AUTHOR]

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In this study, the effect of Ce content on hydrogen induced cracking (HIC) of X80 pipeline steel has been investigated. The results show that as the Ce content increased from 0 wt% to 0.0042 wt%, 0.016 wt% and 0.024 wt%, the HIC susceptibility of tested steels decreased first and then increased. The steel containing 0.016 wt% Ce possessed the lowest HIC susceptibility because Ce modified inclusions, promoted the formation of acicular ferrite, and decreased the number of hydrogen traps and intergranular cracks. • Ce was added to X80 pipeline steel to reduced its HIC susceptibility. • Adding 0.016 wt% Ce to steel reduced the number of intergranular cracks. • The steel containing 0.016 wt% Ce possessed the lowest HIC susceptibility. [ABSTRACT FROM AUTHOR]

This research examines the factors contributing to the exterior material degradation of subsea oil and gas pipelines monitored with autonomous underwater systems (AUS). The AUS have a role of gathering image data that is further analyzed with artificial intelligence data analysis methods. Corrosion and potential ruptures on pipeline surfaces are complex processes involving several competing elements, such as the geographical properties, composition of soil, atmosphere, and marine life, whose eflt in substantial environmental damage and financial loss. Despite extensive research, corrosion monitoring and prediction remain a persistent challenge in the industry. There is a lack of knowledge map that can enable image ausing an AUS to recognize ongoing degradation processes and potentially prevent substantial damage. The main contribution of this research is the knowledge map for increased context and risk awareness to improve the reliability of image-based monitoring and inspection by autonomous underwater systems in detecting hazards and early signs of material degradation on subsea pipeline surfaces. [ABSTRACT FROM AUTHOR]